Spherical composite particles of barium sulfate and silica, and production method therefor

Abstract

The present invention aims to provide spherical particles satisfying the requirements concerning “hydrochloric acid-soluble matter” and “soluble barium salt” described in the standard of “Barium sulfate” in “The Japanese Standards of Quasi-Drug Ingredients 2021”. The present invention relates to spherical composite particles of barium sulfate and silica with the following features: when the spherical composite particles are subjected to a purity test concerning “hydrochloric acid-soluble matter and soluble barium salt” described in the standard of “Barium sulfate” in “The Japanese Standards of Quasi-Drug Ingredients 2021”, the spherical composite particles contain a hydrochloric acid-soluble matter in an amount of 15 mg or less, and a test liquid used in the test concerning “soluble barium salt” has an absorbance of less than 0.03.

1 . Spherical composite particles of barium sulfate and silica with the following features:
 when the spherical composite particles are subjected to a purity test concerning “hydrochloric acid-soluble matter and soluble barium salt” described in the standard of “Barium sulfate” in “The Japanese Standards of Quasi-Drug Ingredients 2021”, the spherical composite particles contain a hydrochloric acid-soluble matter in an amount of 15 mg or less, and   a test liquid used in the test concerning the “soluble barium salt” has an absorbance of less than 0.03.   
     
     
         2 . The spherical composite particles of barium sulfate and silica according to  claim 1 ,
 wherein the spherical composite particles satisfy the standard of “Barium sulfate” in “The Japanese Standards of Quasi-Drug Ingredients 2021”.   
     
     
         3 . The spherical composite particles of barium sulfate and silica according to  claim 1 ,
 wherein the spherical composite particles have a sphericity of 1.10 or less.   
     
     
         4 . A cosmetic product, comprising the spherical composite particles of barium sulfate and silica according to  claim 1 . 
     
     
         5 . A method for producing spherical composite particles of barium sulfate and silica, the production method comprising:
 a first step of washing barium sulfate obtained by a reaction between barium sulfide and sulfuric acid with an aqueous solution of a sulfate of a Group 1 or Group 2 element in the periodic table or with sulfuric acid,   a second step of repulping the washed barium sulfate in a solvent to prepare barium sulfate slurry,   a third step involving: mixing the barium sulfate slurry with silica to give a mixture; spray drying a portion of the mixture; firing the dried mixture at 800° C. to 1100° C.; and subjecting the fired product to a purity test concerning “hydrochloric acid-soluble matter and soluble barium salt” described in the standard of “Barium sulfate” in “The Japanese Standards of Quasi-Drug Ingredients 2021” to obtain a mixture having the following feature (a) or (b),   (a) the mixture contains a hydrochloric acid-soluble matter in an amount of 15 mg or less, and a test liquid used in the test concerning “soluble barium salt” has an absorbance of less than 0.03, or   (b) the mixture contains a hydrochloric acid-soluble matter in an amount of 14 mg or less, and a test liquid used in the test concerning “soluble barium salt” has an absorbance of 0.03 or more;   a fourth step, which is performed when the mixture obtained in the third step has the feature (b), of adding a salt of a Group 1 or Group 2 element in the periodic table to the mixture at a percentage of 0.05 to 0.40% by mass relative to the weight of the raw material barium sulfate;   a fifth step of spray drying the mixture having undergone or not undergone the addition of a salt of a Group 1 or Group 2 element in the periodic table to obtain a dried product, and   a sixth step of firing the dried product at 800° C. to 1100° C.   
     
     
         6 . The method for producing spherical composite particles of barium sulfate and silica according to  claim 5 ,
 wherein the mixing the barium sulfate slurry with silica in the third step is performed while mixing the silica such that the weight percentage of the silica is 1% or more in the total weight of the barium sulfate and the silica in the barium sulfate slurry.   
     
     
         7 . The method for producing spherical composite particles of barium sulfate and silica according to  claim 5 ,
 wherein the silica has an average particle size of 1 to 100 nm.